Flexible nonextensible metal straps



Sept. 30, 1969 v M. ZALTRON 3,469,951

FLEXIBLE NONEXTENSIBLE METAL STRAPS med'marcn s1. 196e lllmnly lli:

INVENTOR MARK: zALmoN 5;, wf/Wm@ United States Patent O 3,469,951 FLEXIBLE NONEXTENSIBLE METAL STRAPS Mario Zaltron, Via Panzza 30, Vicenza, Italy Filed Mar. 31, 1966, Ser. No. 539,065 Int. Cl. B21k 27/00 U-S. Cl. 29-183 2 Claims ABSTRACT OF THE DISCLOSURE The present invention provides a flexible nonextensible metal strap for watch-bands, belts, and tapes. The metal strap comprises a attened continuous spiral, made from a long narrow metal strip of S-shaped cross section, the adjacent turns of which are locked together.

BACKGROUND OF THE INVENTION The present invention concerns improvements in or relating to exible nonextensible metal straps. As is well known, exible, nonextensible metal straps generally have an inner core of a exible fabric or an elastic strip and are in every case complicated and expensive to manufacture. In the case of straps having an appreciable Width the inner core does not ensure perfect contact between each turn and between the coil and the inner core.

Furthermore, in metal straps provided with an inner metallic strip, there is the danger that permanent deformations might occur to the strap due to deformations of the internal core. In addition, possible displacements of the internal core relative to the spirals cannot be excluded.

Other known straps utilize hook shaped members on an inner fabric but are not very exible on account of the relatively large dimensions of the hook shaped members which, for constructional reasons, cannot be reduced beyond a certain limit.

SUMMARY OF THE INVENTION According to the present invention, a flexible non-extensible metal strap comprises individual S-shaped members which are interengaged in a continuous strip. The inter-engaging members are compressed so that they are locked together. The strap has a side view in the shape of a continuous spiral and formed by members having an approximately S-shaped cross-section of small transverse dimensions, the adjacent turns of which inter-engage, ensuring maximum iiexibility of the strap and guaranteeing maximum reliability in the inter-engagement of the turns. On the other hand, the S-shaped members may be of extremely reduced dimensions, so that the strap presents a gentle flexibility and the aesthetic appearance of a fabric.

The strap arranged in this manner is then pressed so that each side of the iiattened spiral becomes disposed in direct contact with the opposite side. Therefore, a strap is obtained comprising two parallel and adjacent layers of inter-engaging members.

Generally spiral coils having an S-shaped cross-section of comparatively large dimensions and with inter-engaging turns have been used to make flexible sheaths, particularly for covering conductors of electricity or hydraulic pipes. However, in the present invention, the spiral is completely flattened and provides a thin strap having appreciable resistance to traction in different positions.

The outer surface of the strap may be decorated with 3,469,951 Patented Sept. 30, 1969 designs of various kinds obtained, for example, by mpressing fluttings or surface abrasions which improve the aesthetic appearance of the strap.

Straps in accordance with the present invention may, for example, be used for trouser belts, wrist watch straps, bracelets, driving belts, tapes for venetian blinds or roller shutters. It is obvious that in each of these uses, the strap may replace corresponding straps in use at the present with appreciable advantages from the point of view of mechanical strength and resistance to wear.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described further, by way of example, with reference to the following drawings in which:

FIG. 1 is a perspective view of a component of the present invention from which the strap is produced;

FIG. 2 is a longitudinal section of the strap before it is compressed;

FIGS. 3 and 4 show a portion of a strap associated with a wrist Watch and for a trouser belt respectively;

FIG. 5 is an example of surface decoration with diagonal iluting;

FIG. 6 is an example of surface decoration with curved fluting;

FIG. 7 is a side view of a different embodiment of the strap; and

FIG. 8 is a front section of the strap shown in FIG. 7.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF INVENTION The strap shown in FIGS. 2 and 3 is built up of interlocking members a, as shown in FIG. l. The members are S-shaped in cross-section and inter-engage so that the bends b and c of the S-shaped section forming a turn engage in the corresponding bends of the adjacent members. After the coil, formed as above, has undergone uniform compression, for example by means of presses or rollers, the strap assumes a very flattened form, as shown in FIGS. 3 and 4 in perspective and in plan views respectively.

The strap obtained in this manner has great ilexibility which is accentuated the smaller the pitch turns of the S-shaped members between turn and turn, and which depends on the cross-sectional dimensions of the members a (FIG. l).

If the strap is used as a wrist watch strap or a belt for trousers, it may also be provided with eyes d (FIG. 4) for the introduction of the center spike of the buckle.

The surface of the strap may be decorated, for example, by the impression of longitudinal fluting e (FIG. 4); diagonals f (FIG. 5); curves g (FIG. 6) or by the application of any other surface decoration.

In the alternative embodiment shown in FIGS. 7 and 8, the strap has individual members shown by h (FIG. 7), one of the bends being provided with a plane upper surface and of appreciable thickness so that it is possible to provide iiuting or recesses i (FIG. 8), by abrasion for decorative or aesthetic elects, especially for straps made of precious metals.

What I claim is:

1. A flexible nonextensi'ble metal strap consisting of a single member having two layers formed `by a flattened tube of spiral wall structure, the spiral portions of the strap consisting of interengaging hook-shaped portions.

3 4 2. A metal strap in accordance with claim 1, wherein D. 34,019 2/ 1901 Bennett 63-5 its surfaces have uted designs. 3,136,139 6/ 1964 Sinner 63-5 References Cited L. DEWAYNE RUTLEDGE, Primary Examiner UNITED STATES PATENTS 5 E. L. WEISE, Assistant Examiner 536,419 3/1895 Cochrane 13S-120 X 2,209,239 7/1940 sferzenbach 13s-120 U'S' C1' X'R' 3,060,069 10/1962 Sindars 13S-120 29-180, 193; 63-3 

